US2547202A - Oil circuit interrupter - Google Patents

Description

M BY

w i] TORN E R. E. FRIEDRICH 2,547,202

OIL CIRCUIT INTERRUPTER April 3, 1951 Filed Sept. 27, 1947 2 Sheets-Sheet 1 fly].

. INVENTOR wnwzsszs;

fofierz E Friedrich.

W/EM

April 1951 R. E. FRIEDRICH 2,547,202

OIL CIRCUIT INTERRUPTER Filed Sept. 27, 1947 2 Sheets-Sheet 2 WITNESSES: INVENTOR WW W Patented Apr. 3, 1951 2,541,202 7 on. orncorr INTERRUPTER Robert E. Friedrich, Pittsburgh, Pa,

assignor to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application September 2?, 1947, Serial No. 776,569

6 Claims. 1

This invention relates to circuit interruptcrs in general, and more particularly, to arc-extinguishing structures and operating mechanisms therefor.

A- general object of my invention is to provide an improved circuit interrupter in which an im proved hydraulic operating mechanism is provided to effect operation of the contact structure.

Another object is to provide an improved arcextinguishing unit in which the contact structure is hydraulically operated and which is provided with venting means to vent the unit fol lowing circuit interruption, which venting means is actuated by-the improved hydraulic operating mechanism.

Still another object is to provide an improved circuit interrupter of the type establishing both a pressure-generating :arc and an interrupting arc with fluid passage means interconnecting the two arcs. In my invention, I provide a separate fluid moving means to .assist in low current i..-- terruption and I provide a separate passage interconnecting the fiuid moving means with the interrupting arc to prevent contamination of the fluid sent by the fluid moving means toward the interrupting are.

A further object is to provide an improved arcextinguishing unit with venting means at op posite ends thereof to provide a chimney venting effect, and to provide hydraulic means which not only efiects separation of the contact structure associated with the unit but also effects opening of the venting means following interruption of the circuit.

Another object is to provide an improved hydraulic operating mechanism for the contact means of a circuit interrupter in which the construction is such as to minimize hydraulic friction losses.

Still a further object is to provide improved circuit interrupter of the type specified in the immediately preceding paragraph in which a separate delayed acting low current piston is incorporated which is actuated following a predetermined opening movement of the hydraulic operating mechanism.

Further objects and advantages will readily be come apparent upon reading the following specification taken in conjunction with the ings, in which:

Figure l is a side elevational view, partly in section, of an improved circuit interrupter enebodying my invention and shown in the closed circuit position;

. closed circuit position;

Fig.3 is a view taken at right angles to that of Fig. 2 with the contact structure shown in the partially open circuit position, and

Fig. 4 is an enlarged fragmentary view taken substantially along the line IVIV of Fig. 3.

Referring to the drawings, and more particularly, to Fig. 1 thereof, the reference numeral I designates a tank filled to the level 2 with a suitable arc-extinguishing fluid 3, in this instance circuit breaker oil. Depending from the cover 4 of the tank I are a pair of terminal bushings 5 which support at their lower ends arcextinguishing units, generally designated by the reference character 6.

The arc-extinguishing units 6 are electrically interconnected in the closed circuit position, as shown in Fig. l, by a bridging member I reciprocally operated in a vertical direction by an insulating lift rod 8. The lift rod 8 may be actuated in a vertical direction by suitable mechanism, not shown, which is responsive to either manual operation or to the existence of excessive current conditions in the protected circuit.

Referring to Fig. 2, which more clearly shows the internal construction of the arc-extinguishing units it will be noted that a conducting con tact foot 9 is threadedly secured and clamped to the lower end of the terminal stud, not shown, which extends interiorly through the terminal bushing 5. integrally formed with the contact foot 9 is the top metallic plate H] of the unit 5. The plate Ill in conjunction with insulating tie rods, not shown, fixedly supports in place a plurality of insulating plates, more fully described hereinafter and defining a relatively vented interrupting chamber, generally designated by the reference numeral H. A stationary contact !3 cooperates with a movable contact M to establish an interrupting are 55 within the inter rupting chamber II, as more clearly shown in Fig. 3. Rigidly secured to the'lower end of the movable contact M is an insulating rod 16, the lower end of which is fixedly secured to another movable contact member I! which makes engagement in the closed circuit position, as shown in with relatively stationary pressuregen crating contacts 18.

The stationary contacts [3 are electrically con nected by a vertical spider construction IS with relatively stationary contacts 29', the latter bearing against the external surface of the movable cally extending passages 28 contact [4 during the downward opening move ment thereof.

The electrical connection between the station-- ary contacts i3, 28 may be effected by strap connectors 2f, the latter being brazed to the outer surfaces of the contacts I8, 20. Preferably, the contacts i8, 25 are pivotally mounted by pins 22 and biased inwardly toward the movable contact structure by torsion springs 23.

The movable pressure-generating contact member ll separates from the stationary pres" sure-generating contacts l8 to establish a pressure-generating are 26 within a relatively confined pressure-generating chamber, generally designated by the reference numeral 2?. It will be noted that there is provided a pair of vertiinterconnecting the pressure-generating chamber 2! with the interrupting chamber ll. Thus, liquid under pres sure from the pressure-generating chamber 2? may flow upwardly within the passages 23, as indicated by the arrows 29, into the interrupting chamber i i to effect extinction of the interrupting arc l draw therein.

Suitable insulating plate structure is provided defining the interrupting chamber i i which very effectively directs liquid into intimate engagement with the interrupting are !5. This insulating plate structure follows the teachings set forth in United States patent application filed December 22, 1945, Serial No. 636,940, now Patent No. 2,467,760, April 19, 19%, by Leon R. Ludwig, Benjamin P. Baker, and Winthrop M. Leeds, and assigned'to the assignee of the instant application. Preferably, this plate structure consists of fibre insulating piates of three different types. The first type, designated by the reference character 3!, has portions removed therefrom to define inlet passages 32, more clearly shown in Fig. 2. Adjacent each inlet insulating plate 3i is, aninsulating orifice plate 33 having an orifice 34 provided therein through which passes the movable contact member 14 during its opening motion.

On the other side of the orifice insulating plate 33 from the inlet plate 3l'is a vent plate, generally designated by the reference numeral 35. Preferably, the vent plate 35 is composite and consists of two identical halves 36 spaced laterally apart to provide a pair of opposed outwardly extending vent passages 31, more clearly shown in Fig. 3.

From the foregoing description, it will be apparent that the oil passes inwardly toward the interrupting arc I5 through the opposed inlet passages 32, thence through the orifices 34 provided by the orifice plates 33 to exhaust outwardly away from the interrupting arc l5 out of the unit 6 through the opposed vent passages 31. Extinction of the interrupting are it soon follows and the circuit is interrupted.

It will be noted that the lower end of the movable contact member ll makes electrical engagement with contact clips 38 and passes downwardly into an operating cylinder 3%. The operating cylinder 39 is threadedly connected at 49 to a cup-shaped metallic casting ii. The lower end of the operating cylinder 39 is closed by an apertured closure cap 22 threadedly secured, as at 53, to the lower end of the operating cylinder 39. Apertures 44 are provided adjacent the lower end of the operating cylinder 39 so that the region below the operating piston 35 freely communicates with the region 55 which is substantially at atmospheric pressure. The operating piston d5 4 has a lost-motion connection with the lower end 4'! of the movable contact member H. The lower end 4? of the movable contact member I! has an enlarged metallic cyindrical member lla rigidly secured thereto having diagonal cuts 43 formed therein. The cuts 43 cooperate with an inwardly extending flange portion 49 of the operating piston to provide a valve means, generally designated by the reference numeral 58 which is closed during the downward opening motion of the operating piston :35 and movable contact member H. The valve means 50 closes during the opening operation by virtue of the fact that the flange portion 49 covers the tops of the cuts or recesses 48. During closing the valve means 58 is open as later described.

A compression spring 52 is provided within the lower end of the operating cylinder 39, having its lower end seated upon the closure cap 42 and having its upper end bearing against an inwardly extending flange portion 53 of the operating piston '65. Thus, during the closing upward motion of the movable contact member H, the spring 52' first raises the operating piston :35 to open the valve means 58 and subsequently after the lost-' 'motion is taken up, strikes the cylindrical member 41a to cause thereby upward closing motion of the contact member ll, the valve means 50 being open during the entire closing operation since liquid can by pass the member 41a through the recesses 48.

My improved hydraulically operated mechanism 54 also includes a pumping piston 55 having an inwardly extending portion 56 which bears against the outer surface of the operating cylinder 39 being guided thereby. A battery of compression springs 5? is provided to bias the pumping piston 55 downwardly in the circuit opening direction to thereby compress liquid within the region 58. This liquid under pressure within the region 58 may pass through apertures 59 pros" vided in the operating cylinder 39 to act downwardly upon the operating piston 45 in the manner previously described.

The pumping piston 55 has a depending cylindrical portion 60 which makes threaded engagement, as at Bl, with an insulating tube 62, the lower end of which makes threaded engagement with a metallic bumper 63. The bumper 63 is preferably threaded, as at 64, adjacent the lower end of the insulating tube 52.

The bridging member I is composite, having an upper conducting portion 65 and a lower insulating portion 65. The portion 65 has an upwardly extending piece iii which passes between a pair of jaw-type stationary disconnect fingers 63, biased toward each other by any suitable means, not shown. The disconnect fingers 6B are electrically connected by a connector 59 to the lower metallic plate 19 of the unit 6.

I have provided a cylindrically-shaped follower member H which has an inwardly extending flange portion i2 at its upper end. The upper edge 3 of the pumping piston 55 picks up the follower member 'H during the closing stroke against the downward biasing action exerted by a compression spring i l. The upper end of the compression spring it bears against the metallic casting M, and the lower end of the compression spring 14 bears against a radially outwardly extending flange portion of the follower member I I.

To facilitate low current interruption when the pressure generated within the pressure-generating chamber 21 by the pressure-generating arc now be explained.

2511s relatively low, I have provided a separate independently movable pumping piston 7.6 which is picked up during the closing stroke by a shoulder portion 11 of the pumping piston 55. Arelatively light compression spring 18 retracts the pumping piston "56 in the closed position, as shown in Fig. 2, forcing the upper end 19 thereof against steps 89 integrally formed with the casting 4i Consequently, during the opening stroke there is a time-delay before the follower member H picks up the pumping piston 75 to force it downwardly by the action of the compression spring 14. The reason for the delayed action of the pumping piston 75 during low current interruption is set forth and claimed in United States patent application filed December 15, 1943, Serial No. 514 366, now abandoned, and continued in patent application Serial No. 6,436, filed February 5, 1948, by Winthrop M. Leeds, Robert .E. Friedrich, .and Francis J. Fry and assigned to the assignee of the instant application.

The downward opening movement of the pumping piston '15 is effective to force oil outwardly through apertures 8| provided in the casting 4| and upwardly as indicated by the arrows 82 through a separate passage means, in this instance consisting 'of two vertically extending passages 83.

By the provision of the passages 83 separate from the passages 28, there is no possibility of fluid within the passages 28 coming from the pressure-generating are 26 contaminating the fluid within the vertical passages 83 moving upwardly from the auxiliary pumping piston 16.

Thus, clean oil is provided by action of the pumping piston 15.

I have provided venting means 84, 85 at opposite ends of the unit 5 to provide a chimney-like venting arrangement, which venting means is hydraulically actuated at the extreme end of the opening operation. This results since I have provided a cylinder 86 secured, as by welding at 81, to the lower plate 19 of the unit 6. The cylinder 96 has apertures 88 provided therein so that during the initial downward opening motion of the pumping piston 55 liquid will not be compressed within the region 89. It is only near the end of the opening operation, after interruption of the arcs has been completed, that the downward opening movement of the pumping piston 55 is effective to compress oil within the region 89 and place the oil within the insulating tubes 95 under pressure. At this time the oil under pressure within the tubes 95 forces the pistons 9| associated with the venting means 84, 85 to open the valves 92 associated with the venting means 84, 85. Thus, at the extreme end of the opening operation contaminated fluid permitted to freely flow out .of the unit by the simultaneous opening of the venting means 84, 85 at opposite ends of the .unit 5.

In similar manner venting means 93 .is pro vided at the lower end of the pressure-generating chamber 2?, as shown in Fig. 3. This permits the pressure-generating chamber 2'! to be freely vented the extreme end or". the opening operation. The pistons 9! associated with the venting means 93 are actuated by oil under pressure within tubes 24 which communicate with the a region 89; Thus, all six of the pistons 9| are simultaneously actuated by the final downward opening travel or" the pumping piston 55.

The-operation of my improved interrupter will In the closed circuit position of the interrupter, as shown in Fig. .2, the electrical circuit therethrough includes conducting contact foot 9, conducting plate it, .shunt =95. stationary contact is, movable contact 14, stationary contacts 20, strap connectors 2i, stationary contacts l8, movable contact member :17, contact .clips 33, casting 4], lower plate it, connectors 59, stationary disconnect fingers 68, upstanding conducting piece 6'! of the bridging member I and through the right-hand arcextinguishing unit 6 in like manner to the other terminal of the interrupter.

When it is desired to open the electrical circuit passing through the interrupter, suitable mechanism, not shown, which is responsive to either manual operation or to the existence of excessive current conditions in the circuit, causes downward opening motion of the lift rod 8. The downward movement of the insulating liftrod 8 causes corresponding downward opening movement of the composite bridging member 1.

The downward movement of the bridging member I permits the battery or" compression springs 51 to force the pumping piston 55 downwardly to compress oil within the region 53. This ,oil under pressure within the region 58 passes through the apertures -52 provided in the operating cylinder 3?). This oil then acts upon the top surface of the operating piston 55 to cause it to move downwardly against the biasing action 62 erted by the compression spring 52. After the lost-motion between the operating piston 45 and the movabfe contact member I? is taken up, the valve means 59 is closed and the downward movement of the operating piston 45 carries the .movable contact H downwardly with it. Since the insulating portion l6 interconnects the contacts 14, H, the pressure-generating are 26 and :the interrupting are [5 will be substantially simultaneously established respectively within the pressure-generating chamber 21 and the interrupting chamber H.

Oil under pressure from the pressure-generating are 26 flows upwardly during high current interruption through the passages '28 to effect extinction of the interrupting are 15 within the interrupting chamber i! in a manner as previously described. During this high current interruption the auxiliary piston 76 is not effective and is merely stalled by the high pressure existing within the unit. One or more tubes 24 provide substantially atmospheric pressure in the region 25 in back of the pistons 55,, "it so that the biasing action exerted by spring 74 is overcome by the high pressure existing within the unit. It is only during low current interruption when the pressure within "the pressure-generating chamber 2? is low that the auxiliary pumping piston it is effective to force oil upwardly through the passages 83 and into the interrupting chamber I i to effect the extinction of theinterrupting arc Hi established therein.

It will be noted that the areas of the pumping piston 55 and the operating piston is are such as to cause considerable travel ofthe contact structure for a much shorter travel of the the pumping piston 55. This gives high speed opening essential for three cycle performance. It will also be noted that the path between the two pistons 55, 35 is short to reduce to a mini mum hydraulic friction losses.

The pumping piston 55 continues to move downwardly under the action of the compression springs 5'! as permitted by downward motion of the insulating portion IE6 of the bridging member 1. Finally, following interruption of the arcs, the conducting piece 51, or the movable disconnect contact, separates from the stationary disconnect fingers 68 to insert two isolating. gaps in the circuit, as more clearly shown by the dotted lines 95 of Fig. 1.

It will therefore be apparent that the circuit is broken within the unit 6 and not at the disconnect contacts 61, 68, the latter separating only following circuit interruption. It will be ob served that following interrupting of the arcs i5,

29 the pumping piston 55 establishes oil pressure within the regions 89 to effect opening of the venting means 84, 85 at opposite ends of the unit to thereby permit contaminated fluid to freely flow out of the unit 6 by the chimneylike vent passages formed. Also as shown in Fig. 3. the venting means 93 will be opened to permit venting of the pressure-generating chamber 27.

Finally, the downward movement of the pumping piston 55 is halted by its striking th portion 91, and the compression spring 52 at this time effects reclosure of the contact structure. In other words, the compression spring 52 first forces the operating piston 45 upwardly to first open the valve means 59 permitting leakage of oil around the lower end 4'! of the movable contact member 11.

After the lost-motion is taken up and the valve means 59 is open, the operating piston 45 picks up the movable contact member 11, forcing the latter upwardly to thereby effect re-engagement of the contacts ll, l8, l4, 13. Hence the electrical circuit is completed through the interrupter in the fully open circuit position thereof, the isolating gaps withstanding the impressed voltage.

During the interruption of low currents, as previously mentioned, the downward movement of the follower member 1 I, as caused by the bias" ing action of the compression spring 14, picks up the auxiliary piston 16 to force fluid up through the passages 83 and toward the interrupting are [5.

A flap valve 98 is provided which closes the region 58 during the opening operation and permits oil to enter the region 58 through holes 99 during the closing stroke.

During the closing operation of the interrupter,

suitable means causes upward closing motion of the lift rod 8. This raises the bridging member l and first causes engagement between the bumper 53 and the insulation portion 68 of bridg ing member 1. Thus, even before the disconnect contacts 81, 68 are engaged, the bumper 63 has been moved upwardly a considerable distance to thereby effect charging of the pumping piston 55. The reason for this is that if excessive current conditions still exist in the circuit during the closing operation and prestriking occurs between contacts 91, 58 to thereby reverse the motion of. the operating mechanism, the pumping piston 55- will have been sufficiently charged at this time of reversal to effect opening of the contact structure in the manner previously described. In other words, if the pumping piston 55 were not partly charged by the time the contacts 67, 68 were sufficiently close together to be conductively bridged by prestriking, the pumping piston 55 would be ineffective to open the contact structure and the interrupter would fail. By partly charging the pumping piston- 55 before there is a possibility of flashover between the disconnect contacts 51, 63, assurance is had that'the breaker will operate in the nor mal manner should reversal of the mechanism take place at an intermediate point in-the closing operation.' v

From the foregoing, it will be apparent that during the closing operation the actuating member 66 causes upward charging movement of the pumping piston 55 to thereby cause opening of the flap. valve 98 to draw oil through the apertures 99 into the region 58. Also the shoulder portion 11 of pumping piston 55 picks up the auxiliary piston 75. Further, the upper edge 13 of pumping piston 55 picks up the follower member H and effects the charging motion thereof.

During the initial downward movement of the pumping piston 55, the compression spring 18 maintains the auxiliary pumping piston 16 against the stops so that there is a predetermined time interval before the piston 76 is effective to pump oil.

From the foregoing, it will be apparent that m improved interrupter is particularly applicable for high speed reclosing operations due to the provision of the venting means 84, and 93. Thus, the gases which tend to contaminate the oil within the unit 6 are rapidly expelled therefrom following extinction of the arcs. To check the contact structure during installation of the interrupter, it is necessary only to thread a long stud, not shown, into the tapped hole H39 and move the two contacts 14, H and the insulating portion l6 vertically. The interrupter is easily installed requiring only that the bridging member I be sufficiently aligned to cause the conducting portion 67 thereof to pass between the disconnect fingers 88, and that the piston 55 is sufiiciently charged before engagement of the disconnect contacts. Neither of these dimensions is very critical.

Certain features of the contact structure in volving the contacts l4, ll tied together by the insulating rod l6,,together with the inverted order ofithe pressure-generating chamber and the interrupter chamber, are set forth and claimed in United States patent application filed February 21, 1947, Serial No. 729,934 by Robert E. Friedrich and Winthrop M. Leeds. Features involving the hydraulic operating mechanism 54 are, in part, covered by United States patent application filed October 30, 1946, Serial No. 706,735, now Patent No. 2,463,029, March 1, 1949, by Francis J. Fry. A further feature involving the part charging of the pumping piston 55 during the closing stroke before engagement of the disconnect fingers 6'1, 68 is described and claimed in United States patent application filed April 4, 1947, Serial No. 739,273 by Winthrop M. Leeds. The feature of broadly providing a chimney effect is described and claimed in United States patent application filed November 21, 1946, Serial No. 711,422, now Patent No.'2,465,218, March 22, 1949, by Robert E. Friedrich. All of the foregoing applications are assigned to the assignee of the instant application.

Although I have shown and described a specific structure, it is to be clearly understood that the same was merely for the purpose of illustration and that changes and modifications may readily be made therein by those skilled in the art without departing from the spirit and scope of the appended claims.

I claim as my invention:

'1. A circuit interrupter having contact means operable to establish an are including a movable contact, an operating piston for actuating the movable contact, an operatin cylinder within which the operating piston moves, a movable pump piston surrounding the operating cylinder and having the region of compression immediately adjacent the external surface of the operating cylinder, and apertures through the operating cylinder so that the travel of fluid between the two pistons will be short to minimize hydraulic friction losses.

2. A circuit interrupter having contact means operable to establish an are including a movable contact, an operating piston for actuating the movable contact, an operating cylinder Within which the operating piston moves, a movable pump piston surrounding the operating cylinder and having the region of compression immediately adjacent the external surface of the operating cylinder, apertures through the operating cylinder so that the travel of fluid between the two pistons will be short to minimize hydraulic friction losses, means biasing the movable contact toward its closed position, and valve means associated with the operating piston to permit fluid leakage around the operating piston during the closing movement of the movable contact.

3. A circuit interrupter including a pair of arcextinguishing units, each unit having contact means operable to establish an are including a movable contact, an operating piston for actuating the movable contact, an operating cylinder within which the operating piston moves, a movable pump piston surrounding the operating cylinder and having the region of compression im mediately adjacent the external surface of the operating cylinder, apertures through the operating cylinder so that the travel of fluid be-- tween the two pistons will be short to minimize hydraulic friction losses, and a movable bridging member electrically connecting the two units in series in the closed circuit position and charging the two movable pump pistons associated with the two units.

4. A liquid break arc-extinguishing unit having contact means including a movable contact member separable to establish an arc, a hydraulic operating mechanism for the movable contact member including an operating piston operatively connected with the movable contact member, an operating cylinder within which the operating piston moves, a movable pumping piston for forcing liquid into the operating cylinder to effect thereby opening motion of the operating piston and movable contact member, means biasing the pumping piston in a direction to separate the contact means, an actuating member to charge the pumping piston during the closing operation of the unit against said biasing means, and another pumping piston operatively related to the pumping piston to assist in low current interruption.

5. A liquid break arc-extinguishing unit having contact means including a movable contact member separable to establish an arc, a hydraulic operating mechanism for the movable contact member including an operating piston operatively connected with the movable contact member, an operating cylinder within which the operating piston moves, a movable pumping piston for forcing liquid into the operating cylinder to effect thereby opening motion of the operating piston and movable contact member, means biasing the pumping piston in a direction to separate the contact means, an actuating member to charge the pumping piston during the closing operation of the unit against said biasing means, a follower member, means biasing the follower member in said direction, and a delayed acting piston picked up after a predetermined travel of the follower member to assist in low current interruption.

6. Aliquid break arc-extinguishing unit having contact means including a movable contact member separable to establish an arc, a hydraulic operating mechanism for the movable contact member including an operating piston operatively connected with the movable contact memher, an operating cylinder within which the operating piston moves, a movable pumping piston for forcing liquid into the operating cylinder to effect thereby opening motion of the operating piston and movable contact member, means biasing the pumping piston in a direction to separate the contact means, an actuating member to charge the pumping piston during the closing operation of the unit against said biasing means, venting means for the arc-extinguishing unit, and means whereby the pumping piston opens the venting means near the end of its opening motion in said direction to vent the unit.

ROBERT E. FRIEDRICH.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,102,768 Trencham et al. Dec. 21, 1937 2,147,497 Prince et al. Feb. 14, 1939 2,239,554 Duffing Apr. 22, 1941 2,258,226 Skeats Oct. 7, 1941 2,386,611 Ileman Oct. 9, 1945 2,420,889 Leeds May 20, 1947 2,422,569 Leeds June 17, 1947 2,465,218 Friedrich Mar. 22, 1949 2,477,788 Cumming Aug. 2, 1949

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